Fuel vapor loss elimination system



Sept. 26, 1961 H. H. DIETRICH ET AL 3,001,519

FUEL VAPOR Loss ELMINATIoN SYSTEM 2 Sheets-Sheet l Filed Aug. 8, 1960 SCP- 26, 1961 H. H. DIETRICH ETAL 3,001,519

FUEL VAPOR LOSS ELIMINATION SYSTEM Filed Aug. 8, 1960 2 Sheets-Sheet 2 A Tram/gv 3,001,519` FUEL VAPOR LOSS ELIMNATION SYSTEM Howard H. Dietrich, Rochester, N .Y., and Charles J.

Brady, Phoenix, and Philip J. Garthe, Mesa, Ariz., as-

signors to General Motors Corporation, Detroit, Mich.,

a corporation of Delaware Filed Aug. 8, 1960, Ser. No. 48,238 Claims. (Cl. 12S- 136) The present invention relates to a system for preventing emission of fuel vapors into Ithe atmosphere pursuant to the operation of an internal combustion engine. Mo-re specifically, the present invention relates to a fuel system whereby such vapors are drawn from the fuel tank and carburetor float bowl and consumed by the engine during normal operation and further wherein such vapors are withdrawn from the fuel tank and carburetor iioat bowl for a predetermined period after the engine has been shut off.

In addition to the unburned hydrocarbons that emanate from the exhaust systems of vehicles, a considerable source of contaminating fuel vapors are found to originate from the fuel storage portions of a vehicle fuel system which are normally vented to the atmosphere. 'I'he present fuel system has been developed in order to prevent these fuel vapors from being vented to the atmosphere and further to provide means whereby these vapors may be consumed by the engine and thus produce useful power.

Systems for drawing fuel vapors into the engine where they are consumed during normal engine operation are old. Many such workable systems have been developed. However, a more serious and unsolved aspect of this problem is the emission of fuel vapors to the atmosphere after a vehicle engine has been shut off. Under this condition fuel in the system is still subjected to the residual engine heat and is caused to vaporize and pass into the atmosphere contributing to the contamination of the latter.

In addition to consuming fuel vapors during normal engine operation the present invention provides a unique means whereby these vapors continue to be drawn off and stored after the engine has been shut oi and further which vapors are subsequently adapted to be drawn into the intake manifold and consumed bythe engine when the latter is restarted.

ln general, the present invention includes vapor conduit means communicating with the fuel tank and carburetor iloat bowl and also with the -intake manifold whereby fuel vapors are adapted to be drawn into the manifold and consumed by the engine. Means is provided for maintaining a relatively slight manifold depression in the conduit means during engine operation. In one form of the invention, a Variable Volume member is provided in said conduit means and during normal engine operation is maintained at a reduced volume while at the Sametime transmitting fuel vapors therethrough. Upon shutting o of the engine, the variable Volume member is adapted to gradually expand to its normal volume and thereby continue to draw off fuel tank and carburetor fuel vapors until the engine temperature has been reduced to generally ambient levels.

in another modification of the invention, pump means remains energized for a limited period after the engine is shut off whereby fuel vapors continue to be delivered to a fuel vapor absorbing device.

The details as well as other objects and advantages of the present invention will be apparent from a perusal of the detailed description which follows.

In the drawings:

FIGURES 1, 2 and 3 are diagrammatic representations of various modifications of the subject fuel system.

A conventional carburetor is indicated generally at 10 and is mounted on an engine intake manifold 12 to which States Patent Patented Sept. 26, 195i lil@ the carburetor supplies a suitable fuel-air mixture. Carburetor 1@ includes a fuel bowl i4 supplied with fuel from a conduit i6. fFhe quantity of fuel flow into bowl 14 is controlled in the normal manner by a tioat controlled inlet valve, not shown. A fuel pump 1S supplies fuel to conduit i6 and in tuin draws fuel from a fuel tank 20 through a conduit 22. Fuel tank 2li is adapted to be filled in the norm-al manner through a filler pipe 24 normally closed by a vented cap 26.

`Fuel tank .20 and carburetor fuel bowl 14 are communicated above the fuel level by a conduit means 28 with intake manifold 12. ln general, conduit means 28 enables fuel vapors to be drawn from the fuel tank and carburetor iioat bowl into the intake manifold. However, the manner in which these vapors are withdrawn is important and constitutes the subject matter of the present invention.

For venting purposes and so as not to otherwise interfere with the proper operation of the fuel system, only a slight vacuum is necessary in conduit means 28 to secure the desired venting operation. For illustrative purposes, this vacuum level may be in the nature of 11/2 inches of water. This vacuum level in conduit means 28 is maintained in part by the provision of orifices 30 and 32 disposed in branch portions 34 and 36 of the conduit means.

To further regulate the level of vacuum in conduit means 28, a regulator 38 is provided and includes a diaing 42 `and defines a chamber 50 therewith. Valve member 41B includes a second valve portion `52 formed at one end thereof and adapted to seat against casing 42 to block the flow of vapor through the regulator when the engine is shut olf. Adjustable valve member 4th is urged by a spring 54 in a direction causing the second valve portion 52 to seat. During norm-al engine operation, however, manifold vacuum acting in chamber 56 is sufficient to operate on diaphragm S8 and open valve 40 against the force of spring S4. Thus, as manifold vacuum increases, the tapered portion 44 of valve 40 is caused to be moved upwardly within the tapered portion of casing 46 and to thereby reduce the vacuum force in conduit means 28 anteriorly of the regulator to maintain the vacuum force in this portion of the conduit means at a relatively steady and reduced value. A threadably adjustable needle Valve 60 is mounted in casing 42 and coacts with vacuum passage 62 to provide for the basic adjustment of the vacuum force acting on regulator diaphragm 58.

A variable volume member 64 is disposed in conduit means 28 anterior of regulator 38. In the illustrated embodiment of the invention, the variable volume member 64 may be an open ended iiexible plastic tube or cylinder through which fuel vapors may continuously flow during normal engine operation. The construction or consistency of the flexible member 64 is such that the pressure dilferential occasioned by the vacuum within the bottle and atmospheric pressure without will cause the latter to collapse to a predetermined extent thereby reducing the actual volume of the bottle. Thus, during normal engine operation tube l64 will be collapsed as shown in dotted lines at 66 at the same time permitting fuel vapors to be drawn therethrough and discharged into intake manifold 12. However, upon the shutting off of the engine, manifold vacuum is eliminated whereby spring 54 will cause valve portion '52 of regulator 3S to Seat blocking the flow of vapor through the regulator. At the same time, in-

the latter to gradually expand `and return to its normal shape and volume. This gradual expansion of tube or cylinder 64 will continue to cause any vapors in the fuel tank and carburetor float bowl to be drawn thereinto and -trapped until such time as the engine is restarted.

The rate and length of time through which cylinder member 64 will continue to expand and draw off fuel vapors will be determined by the size of fuel tank and float bowl bleeds 68 and 70 as well as the volume of the member itself. For illustrative purposes, member 64 can conveniently be made of a sufiicient size to insure that vapors will continue to be drawn off for a period of an hour during which time the temperature of the engine will be reduced to substantially ambient levels under which conditions fuel vaporization is considerably reduced.

It is apparent that the system of FIGURE 1 has been diagrammatically represented and that many variations of the specific elements may be utilized and specifically various forms of variable volume chambers 64 may be employed.

An alternative to the modification of FIGURE 1 in which fuel tank and carburetor float bowl vapors are caused to continue to be drawn off after the engine has been shut off may be achieved through the modifications of FIGURES 2 and 3. A basic difference between the modification of FIGURE 1 and those of FIGURES 2 and 3 is that in the latter instances, after the engine has ceased operation, the fuel vapors continue to be drawn off by means of a pump rather than a vacuum accumulator. In the modification of FIGURES 2 and 3, a pump is disposed in series with the fuel tank and carburetor float bowl vapor lines and is so arranged that it Will continue to operate for a predetermined period after engine operation has ceased.

Referring now to FIGURE 2, a carburetor is indicated generally at 72 and is mounted on engine intake manifold 74 to which the carburetor supplies a suitable fuel-air mixture. Carburetor 72 includes a oat bowl 76 supplied with fuel from a conduit 78. The quantity of fuel flow into bowl 76 is controlled in the normal manner by a float controlled inlet valve, not shown. A fuel pump 80 supplies fuel to conduit 78 and in turn draws fuel from fuel tank 82 through a conduit 84. Fuel tank 82 is adapted to be filled in the normal manner through a filler pipe 86 normally closed by a vented cap 88.

Fuel tank 82 and carburetor lioat bowl 76 are communicated above the fuel level by a conduit means 90 with intake manifold 74. In general, conduit means 90 permits fuel vapors to be drawn from the fuel tank and carburetor float bowl into the intake manifold when the engine is operating.

As with the modification of FIGURE 1, orifices 92 and 94 are provided in branch portions 96 and 98 of conduit 90 to maintain a slight vacuum in the conduit for the withdrawing of fuel vapors.

Vacuum regulator 100 is the Same as that described with respect to the modification of FIGURE 1 and therefore no further description of this device need be undertaken.

A pump 102 and a fuel absorbing device 104 are disposed in conduit means 90 intermediate manifold 74 and carburetor 72. Pump 102 may be of any well known electrical type but more preferably may be of the solenoid type shown in copending application Serial No. 841,- 794 Parker, filed September 23, 1959. Pump 102 is connected through suitable leads 106 and 108 with an electrical power source such as the vehicle battery 110, Leads 106 and 108 are in turn interconnected through a thermostatic time delay switch device indicated generally at 112. While the details of thermostatic switch 112 do not, per se, constitute a part of the present invention, the switch may include a heating coil 114 which, through lead 116 and ignition switch 118, also communicates with battery 110. Coil 114 may be wrapped around a temperature sensitive element 120 which, when ignition switch 118 is closed, will move switch contact 122 into engagement with contact 124 thereby energizing pump 102. On the other hand, opening of the ignition switch 118, signifying the shutting off of the engine, will interrupt the flow of current to thermostatic switch coil 114. The temperature sensitive element 120 is, however, constructed such that contacts 122 and 124 will remain engaged for a predetermined period after the engine has been shut olf before the switch will open to -de-energize pump 102. It would be completely feasible for thermostatic switch 112 to remain closed an hour after the engine has been shut olf. With pump 102 energized air will be drawn through fuel tank cap vent 126 and small bleed 128 in the iioat bowl fuel reservoir whereby fuel vapors will be caused to iiow through conduit means 90 and into device 104.

In the modification of FIGURE 2, fuel absorbing device 104 includes a casing 130 filled with gasoline absorbing material such as cotton batting 131 or a suitable gasoline desiccant. The use of a desiccant is more particularly considered in the description relating to the modification of FIGURE 3. A first conduit 132 communicates device 104 with vacuum regulator 100 which, during normal engine operation, will cause vapor laden air to be drawn through the device and the regulator and to be discharged into intake manifold 74. A second conduit 134 communicates device 104 with an atmospheric vent device 136. Device 136 includes a pair of casings 138 and 140 having a diaphragm 142 peripherally clamped therebetween. An additional casing 144 coacts with casing 140 to define a chamber 146.

Casing includes an upstanding boss portion 148 communicating with chamber 146 and also with a chamber 150 defined by casing 140 and diaphragm 142. Casing 140 is vented to the atmosphere through an opening 152. A valve member 154 is centrally xed to diaphragm 142 and includes a `disc portion 156 adapted to coact with boss 148 to control the flow of air through the vent device. A spring member 158 is disposed within casing 138 and normally biases the diaphragm and valve to a posi-V tion openly communicating chambers 146 and 1501.

Chamber 160, defined by diaphragm 142 and casing 138, communicates through a suitable vacuum conduit 162 with manifold 74 whereby under normal operating conditions the vacuum acting on diaphragm 142 will retain valve 154 in a closed position shutting off the communication of chamber 146 to the atmosphere.

The operation of the venting device is as follows: assuming the engine to be operating, atmospheric vent device 136 is closed. At the same time, pump 102 is operative to pump air through conduit means 90, gasoline absorbing device 104 from whence the vacuum regulator 100 will draw air and any entrained gasoline vapor into the intake manifold. When the engine is shut off, as already noted, thermostatic time delay switch 112 will maintain pump 102 operating for a predetermined period whereby fuel vapors will continue to be drawn through conduit means 90. However, with the engine inoperative, fuel regulator 100' is inoperative to transmit air or Vapor. At the same time, spring 158 of atmospheric Venting device 136 opens Valve 154 communicating conduit 134 to the atmosphere. Thus pump 102 will force fuel vapor laden air through device 104 wherein gasoline vapors will be absorbed and relatively pure air discharge through the device to the atmosphere. Y

Chamber `104 is subject to high manifold vacuum during most normal vehicle operating conditions, i.e., 15 of mercury vacuum or higher. These Values of vacuum vaporize and'tend to keep chamber 104 in a dry state or highly Vaporized condition such that fuel particles are not absorbed by the absorbent material. However, when the engine isk shut off and manifold vacuum no longer exists, chamber 104 will be at atmosphericpressure or slightly higherbecause, of the pump and fuel vapor will be absorbed into the absorbent material. Air

minus vapor will then be discharged to through conduit 134 and'devie .136.,

It islevident `that chamber 104 Acan be a container filled with light oil as an absorbent of gasoline vapor and that the vapor'canv be admitted to chamber 104 at the bottom such that it will bubble through the oil.` AUnder high vacuum, the gasoline being lighter will tend to rise and boil olf the diluted mixture int'o'the engine. When the engine is shut olf and vacuum ceases, the vapors will be absorbed in the oil and remain absorbed thus permitting flow of air minus vapor through conduit 134 to device 136.

Another modification is shown in FIGURE 3 and differs in two ways from the modification of FIGURE 2. First, instead of using a cotton batting type material for absorbing fuel vapors, a desiccant material is utilized which when cool will absorb the gasoline vapors and when heated will yield up the vapors. Secondly, the vacuum regulator device is eliminated. The present modification will be described in detail only to the extent that it differs from the modification of FIGURE 2. Otherwise, identical numerals will be applied to the elements described in the modification of FIGURE 2. An adjustable needle valve 164 is disposed in conduit 90 for controlling the vacuum level therein. A thin wall tube l166 is provided in conduit means 90 and is filled with a desiccant material 168 such as silica gel. The silica gel is adapted to scrub the gasoline vapor laden air forced through conduit means 90 by pump 102. When the gel is maintained at normal temperature it will absorb the fuel vapors while permitting the air to pass therethrough. Tube 166 is surrounded by a heating coil '170 which connects through lead 172 with ignition switch 118. When ignition switch 118 is closed coil 170 will be heated and the silica gel rendered impotent to absorb fuel vapors. On the other hand, when the ignition switch is open, gel 168 cools rapidly whereby it will absorb the fuel vapors.

Tube 166 communicates through a first passage 174 with atmospheric venting device 136 and through a second passage 176 with the intake manifold 74. As already noted with the modification of FIGURE 2, when the engine is operative vent device 136 will be closed in which case gasoline vapor laden air will ilow through tube 166, passage 176 and be discharged into intake manifold 74. On the other hand, when the engine is inoperative vent device 136 will be opened at the same time the silica gel will, being cool, absorb fuel vapor While gasoline vapor-free air will be pumped through vent device 136 to the atmosphere for a predetermined period.

A restriction I178 is provided in manifold vacuum passage 176 whereby air will be discharged through vent device 136 when the latter is open rather than into the intake manifold.

We claim:

l. A fuel system for an internal combustion engine comprising an intake manifold, a carburetor for supplying a combustible mixture to said intake manifold, said carburetor including a fuel reservoir, a fuel tank, a pump for delivering fuel from the fuel tank to the carburetor fuel reservoir, vent conduit means communicating with the fuel reservoir and fuel tank above the fuel level, said vent conduit means being adapted to communicate with said intake manifold, a fuel vapor storing device disposed in said vent conduit means intermediate the carburetor and intake manifold, said device including means for causing fuel vapors to flow through said conduit means for a predetermined period after said engine has been rendered inoperative.

2. A fuel system for an internal combustion engine comprising an intake manifold, a carburetor for supplying a combustible mixture to said intake manifold, said carburetor including a fuel reservoir, a fuel tank, a pump for delivering fuel from the fuel tank to the carburetor fuel reservoir, vent conduit means communicating with the fuel reservoir and fuel tank above the fuel level, said vent atmosphere conduit means being adapted to communicate with said intake manifold, means for reducing the vacuum in the conduit meanswhe'reby the reservoir and fuel tank are maintained under a light vacuum during normal engine operation, a, fuel vapor storing device disposed in said vent conduit means intermediate the carburetor and intake .manifoldysaid `device including means for causing fu'elvapor's' 'to iiowgthroughfsaid conduit means for a predetermined period after'said engine has been rendered iuoperative.

3. A fuel system for an internal combustion engine comprising an intake manifold, a carburetor for supplying a combustible mixture to said intake manifold, said carburetor including a fuel reservoir, a fuel tank, a pump for delivering fuel from the fuel tank to the carburetor fuel reservoir, vent conduit means communicating with the fuel reservoir and fuel tank above the fuel level, said vent conduit means being adapted to communicate with said intake manifold, a fuel vapor storing device disposed in said vent conduit means intermediate the carburetor and intake manifold, said device including means for causing fuel vapors to iiow through said conduit means for a predetermined period after said engine has been rendered inoperative, said device being substantially inoperative to store fuel vapor during normal engine operation.

4. A fuel system as set forth in claim 1 in which said fuel flow causing means includes a pump.

5. A fuel system as set forth in claim l which includes a venting mechanism disposed in said vent conduit means posterior of said fuel vapor storing device whereby fuel free air from said device is discharged to the atmosphere when said engine is inoperative.

6. A fuel system as set forth in claim l in which said fuel flow causing means includes an electric pump adapted to pump air through said conduit means, said pump means for energizing said pump when the engine is operative and for maintaining the pump energized for a predetermined period after the engine is inoperative.

7. A fuel venting system for an internal combustion engine comprising an intake manifold, a carburetor mounted on said intake manifold and adapted to supply a fuel-air mixture thereto, said carburetor including a fuel reservoir, a fuel tank, means for delivering fuel from said fuel tank to said reservoir, conduit means communicating said fuel tank and said reservoir about their respective fuel levels to the intake manifold, said fuel tank and carburetor reservoir respectively including restricted atmospheric bleeds, means for controlling the manifold depression in said conduit means, and a variable volume member disposed in said conduit means, said variable volume element being maintained at a reduced volume by manifold depression during normal engine operation and being adapted to gradually expand to its normal volume and to thereby maintain air flow through the conduit means for a predetermined period after said engine is shut olf.

8. A fuel venting system for an internal combustion engine comprising an intake manifold, a carburetor mounted `on said intake manifold and adapted to supply a fuel-air mixture thereto, said carburetor including a -fuel reservoir, a fuel tank, means for delivering fuel from. said fuel tank to said reservoir, conduit means communicating said fuel tank and said reservoir about their respective fuel levels to the intake manifold7 said fuel tank and carburetor reservoir respectively including restricted atmospheric bleeds, a regulator disposed in said conduit means for controlling the manifold depression in said conduit means, and a variable volume member disposed in said conduit means intermediate said regulator and said carburetor, said variable volume element being maintained at a reduced volume by manifold depression during normal engine operation and being adapted to gradually expand to its normal volume and to thereby maintain air flow through the conduit means for a predeters,oo1,519

mined -period after said engine is shut olf, vSaid regulator being disposed intermediate the variable volume element and the intake manifold and further being adapted t0 blockV aiI ow therethrough when said engine is Shut O.

9. A fuel system as set forth in claim l in which the vapor storing device includes a container filled with a desiccant material through which the fuel vapor laden air from the reservoir and fuel tank is adapted to pass.

8 Y 10. A fuel system as set forth in claim 9 in which a. heating coil surrounds said container, means for energizing said coil when the engine is operative whereby the desiccant is unable to absorb fuel vapors until the engine 5 is Shut oi.

No references cited.

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Disclaimer 3,001,519.-H0wmd H. Dietrich, Rochester, N .Y., and @hartes J. Brady, Phoenix, and PIL/Zip J, GaN/w, Mesa, Ariz. FUEL VAPOR ELIMINA- TION SYSTEM. Patent dated Sept. 26, 1961. Disclaimer led N 0V.

26, 1963, by the assignee, General Motors orpomtion. Hereby enters this disclaimer to claims l, 2, 3, 4, 5, and 9 of said patent.

[Oytcat Gazette Febmm'y 4i, 1.964.] 

